Adamant Crystal, Lustrous Globe, and Griseous Core were bag items in Legends Arceus because the game didn't have held items at all, but when they were added to SV, they became held items required to be held in order to change the Pokemon's forms. They provide the 20% boost to move power same as Adamant Lustrous and Griseous orbs, but change the forms as well, while Griseous orb no longer does of course.
Works properly with crystal/globe/core moved to held_form_items from key_form_items like the following files:
key_form_items.json
held_form_items.json
Adamant Crystal, Lustrous Globe, and Griseous Core were bag items in Legends Arceus because the game didn't have held items at all, but when they were added to SV, they became held items required to be held in order to change the Pokemon's forms. They provide the 20% boost to move power same as Adamant Lustrous and Griseous orbs, but change the forms as well, while Griseous orb no longer does of course.
Works properly with crystal/globe/core moved to held_form_items from key_form_items like the following files:
key_form_items.json
held_form_items.json